Towards negative-carbon biohydrogen: A dual-function wollastonite strategy for enhanced fermentation and CO2 sequestration

[Geoengineering News]

https://www.sciencedirect.com/science/article/abs/pii/S1385894726036259

Authors: Weiming Li, Can Jin, Huida Duan, Fangcao Li, Zhangxun Huang, Haodong Zhao et al.

16 April 2026

https://doi.org/10.1016/j.cej.2026.176164

Highlights

•Wollastonite as a pH buffer boosts bio-hydrogen production rate and yield.

•Metabolic flux shifts from lactate to acetate, enhancing H2 production.

•In-situ CO2 sequestration is achieved via wollastonite-induced mineralization.

•A two-stage strategy co-optimizes H2 production and CO2 sequestration.

•LCA confirms a 37% process energy saving and lower environmental impacts.

Abstract

Dark fermentation for biohydrogen requires continuous alkaline dosing to control process acidification and expensive separation units to remove co-produced CO2, resulting in high operational costs and energy consumption. Here, we introduce wollastonite as a dual-function agent to simultaneously enhance H2 yield and capture CO2. An optimal dosage of 10 g/L was identified, which shortened the lag phase from 23.13 to 12.38 h and increased the hydrogen yield from 158.11 ± 3.44 mL/g glucose-consumed to 210.75 ± 15.87 mL/g glucose-consumed. Mechanistically, wollastonite buffered the system pH, steering metabolic flux away from lactate towards acetate synthesis by enriching Clostridium and suppressing Lactobacillus. Wollastonite also enabled in-situ CO2 sequestration by precipitating it as CaCO3. However, maximal CO2 capture was achieved at a higher dosage (≥15 g/L), which passively reached the required neutral pH but compromised the hydrogen yield. This created a conflict with the optimal 10 g/L dosage for hydrogenesis. To prioritize the primary goal of green hydrogen production, a two-stage strategy was developed. This approach first uses the optimal 10 g/L dosage for maximal fermentation, followed by a post-fermentation pH adjustment from 6.54 ± 0.18 to 7.0 to induce carbonation. The optimized process successfully sequestered 0.49 ± 0.05 of CO2 per liter of medium, thereby increasing the H2 content in the final biogas to a high of 58.2 ± 1.1%. Finally, a life cycle assessment (LCA) validated the environmental superiority of this strategy, confirming a significantly lower Global Warming Potential (GWP) for the entire process. This work thus provides a proof-of-concept for a pragmatic strategy that co-optimizes hydrogen production and carbon capture in a single, sustainable biorefinery process.

Source: ScienceDirect